Client: Perfect Circle JV on behalf of the Internal Drainage Board Contract
Value: Circa £210k
Role: Principal Contractor
The scheme involved site investigation works for the replacement of the Hobhole Pumping Station and associated infrastructure. The investigation supported design of the new pumping station, cofferdam, crane and piling mats, and access improvements.
Challenges and Site Conditions:
The works were located partly within the Hobhole Drain watercourse and associated flood defences, requiring over-water drilling operations and access within a Site of Special Scientific Interest (SSSI). Variable water levels and tidal influence added complexity to accurate sampling and depth measurements.
Our Approach
- Constructed and operated floating working platforms using modular pontoons fitted with guard rails and spud legs.
- Delivered 6 no over-water cable percussive drilling to depths of 20m below bed level.
- Managed safe craning operations for rig and plant placement.
- Drilled 10 no cable percussive drilling to depths of up to 25 m bgl.
- Excavated 10 no Trial Pits to 4 m, 8 no sheet pile wall inspection Trial Pits to 1.5 m
- Delivered 30 no Road Cores with DCP’s to confirm road surface make-up and subbase integrity.
- Organised local traffic management including road closures and diversions to facilitate the road coring operations.
- Coordinated closely with the Environment Agency and ecological clerk of works to ensure compliance with SSSI and FRAP requirements.
- Provided UKAS accredited geotechnical and contamination laboratory testing services on appropriate recovered soil and groundwater samples.
Outcome
All over-water and land-based investigations were successfully completed with no environmental incidents. AF Howland’s innovative access solutions enabled safe, accurate drilling in challenging tidal and flood-prone conditions, providing robust design data for the new pumping station.